3 ms·

GP said, "cannot function." How did cellphones work before they came with GPS?

geofft 9y ago
They registered with the nearest cell towers, and ask them to watch signal strength so they can make handover work. This is coarse location information (since the company that runs the cell towers knows where their own cell towers, and uses your current tower registration to figure out which cell tower to send a call to), and can be made a little more fine-grained if you use signal strength from the various towers and triangulate. This does not involve the Global Positioning System or other satellite-based positioning systems at all. If it does not do this, it is not a cellular phone. There are other types of portable phones that don't work this way, like cordless landline phones (the base doesn't know where it is, just that it's plugged into a phone jack) or satellite phones. But the "cellular" part refers specifically to dividing up the terrain into cells, finding which cell the phone is in, and assigning it to a tower based on that determination. (This is all pretty irrelevant to the point I was making above that cellular network operators can easily choose not to use the location information or signal strength information for anything other than routing calls, and that deciding that they can just use the information however they want would be creepy.)
- rhizome 9y ago
  And that's fine, but none of this addresses the assertion that cellphones can't work without GPS tracking.
  - geofft 9y ago
    No such assertion was made.
  - khedoros1 9y ago
    GPS tracking is a complete red herring; you're focusing on the wrong thing. No one ever claimed that GPS was necessary. Here's the statement that was made: "Your cell phone cannot function without actually knowing where you are (to some approximation)". That "approximation" is: "Which cell towers can hear your phone transmit, and how strong is the signal?" Your cell phone would work just as well as a phone if you disabled the GPS chip, but your location can be estimated by triangulating from signal strength. It's not nearly as precise, or as accurate, as a GPS-provided location would be, of course.
    - rhizome 9y ago
      No one ever claimed that GPS was necessary The context of this thread is Android and Apple's tracking of location history and I'm just trying to stay on topic. Not without downvotes, natch. This isn't Reddit, I'm not an idiot, and I know how cellphones work. Try to be more charitable.
      - deleted 9y ago
        [deleted]
  - michaelcampbell 9y ago
    > And that's fine, but none of this addresses the assertion that cellphones can't work without GPS tracking Perhaps because that was never asserted. > Your cell phone cannot function without actually knowing where you are (to some approximation) at all times.
  - someguydave 9y ago
    Not GPS tracking. Simply tracking the fact that you transmitted a signal to a particular cell tower (the one nearby in radio terms) is sufficient to narrow your location considerably.
wvenable 9y ago
Your assumption is that GPS is required to know where you are. But each cell tower has a well known physical address and your phone connects to multiple towers making it trivial to triangulate your location. Much less exact than GPS and highly dependent on cell density, etc. https://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=5519760&KC=&FT=E&locale=en_EP# https://worldwide.espacenet.com/publicationDetails/biblio?CC... But even just the connection cell tower number is enough to determine whether or not you're at home or work.

They registered with the nearest cell towers, and ask them to watch signal strength so they can make handover work. This is coarse location information (since the company that runs the cell towers knows where their own cell towers, and uses your current tower registration to figure out which cell tower to send a call to), and can be made a little more fine-grained if you use signal strength from the various towers and triangulate. This does not involve the Global Positioning System or other satellite-based positioning systems at all. If it does not do this, it is not a cellular phone. There are other types of portable phones that don't work this way, like cordless landline phones (the base doesn't know where it is, just that it's plugged into a phone jack) or satellite phones. But the "cellular" part refers specifically to dividing up the terrain into cells, finding which cell the phone is in, and assigning it to a tower based on that determination. (This is all pretty irrelevant to the point I was making above that cellular network operators can easily choose not to use the location information or signal strength information for anything other than routing calls, and that deciding that they can just use the information however they want would be creepy.)

rhizome 9y ago
And that's fine, but none of this addresses the assertion that cellphones can't work without GPS tracking.
- geofft 9y ago
  No such assertion was made.
- khedoros1 9y ago
  GPS tracking is a complete red herring; you're focusing on the wrong thing. No one ever claimed that GPS was necessary. Here's the statement that was made: "Your cell phone cannot function without actually knowing where you are (to some approximation)". That "approximation" is: "Which cell towers can hear your phone transmit, and how strong is the signal?" Your cell phone would work just as well as a phone if you disabled the GPS chip, but your location can be estimated by triangulating from signal strength. It's not nearly as precise, or as accurate, as a GPS-provided location would be, of course.
  - rhizome 9y ago
    No one ever claimed that GPS was necessary The context of this thread is Android and Apple's tracking of location history and I'm just trying to stay on topic. Not without downvotes, natch. This isn't Reddit, I'm not an idiot, and I know how cellphones work. Try to be more charitable.
    - deleted 9y ago
      [deleted]
- michaelcampbell 9y ago
  > And that's fine, but none of this addresses the assertion that cellphones can't work without GPS tracking Perhaps because that was never asserted. > Your cell phone cannot function without actually knowing where you are (to some approximation) at all times.
- someguydave 9y ago
  Not GPS tracking. Simply tracking the fact that you transmitted a signal to a particular cell tower (the one nearby in radio terms) is sufficient to narrow your location considerably.

wvenable 9y ago

Your assumption is that GPS is required to know where you are. But each cell tower has a well known physical address and your phone connects to multiple towers making it trivial to triangulate your location. Much less exact than GPS and highly dependent on cell density, etc. https://worldwide.espacenet.com/publicationDetails/biblio?CC=US&NR=5519760&KC=&FT=E&locale=en_EP# https://worldwide.espacenet.com/publicationDetails/biblio?CC... But even just the connection cell tower number is enough to determine whether or not you're at home or work.